Solvent-circulating system



5 Sheets-Sheet 2 Filed Jan. 50, 1964 HA\RRY SZCZEPANSKI INVENTOR.

Nov. 1, 1966 H. SZCZEPANSKI 3,282,290

SOLVENT-CIRCULATING SYSTEM Filed Jan. 50, 1964 5 Sheets-Sheet 5 HARRY SZCZEPANSKI INVENTOR.

BY 4,,M W M United States Patent 3,282,290 SOLVENT-CIRCULATING SYSTEM Harry Szczepanski, 75,5 Oakleigh NW.,

Grand Rapids, Mich. Filed Jan. 30, 1964, Ser. No. 341,347 4 Claims. (Cl. 137-565) This invention relates to the construction of pumping systems, and has been developed in conjunction with machines for removing accumulations of paint from spray masks. These machines conventionally include a spray chamber in which the masks are temporarily mounted for the cleaning operation. A spray system projects a spray of solvent against the masks, with the drainage returning to be re-circulated. The present invention is concerned with this re-circulating system, and is arranged to make the most economical use of power in the form of the compressed air normally available in industrial establishments.

One of the major difficulties in the design of pressurized circulating equipment has been the protection of the equipment itself from the action of the solvent. Solvents for paints, lacquers, and enamels have a nortorious tendency to attack sealing devices and materials, and this invention provides a structure that minimizes this tendency. The invention further provides a maximum opportunity for suspended particles of paint to settle out, rather than be continuously re-circulated with the liquid. This material acts somewhat like a mild abrasive, and isolating it from the moving components prolongs the life of the equipment.

The vapor losses from these machines is also a problem. This invention is readily adapted to precise pressure control, and the pump itself is arranged to minimize vapor losses. Vapor not only requires ventilation to protect operating personnel, but also represents a loss of expensive material.

The several features of the invention will be analyzed in further detail through a discussion of the particular embodiment illustrated in the accompanying drawings. In the drawings:

FIGURE 1 presents a sectional elevation of the lower portion of the pumping device associated with the invention.

FIGURE 2 presents a sectional elevation of the upper portion of the pumping device shown in FIGURE 1.

FIGURE 3 is a top view of the equipment shown in FIGURE 2.

Referring to the drawings, the spray machine has a cabinet having an elevated floor 11 defining the bottom of a spray chamber 12. Arrangements of spray guns and hanging devices for temporarily supporting spray masks are conventional, and form no 'part of this invention. The back wall 13 of the spray chamber 12 is interrupted to form an opening at 14, and a darn 15 controls the level of the liquid shown at 16. Solvent sprayed within the chamber 12 drains down onto the floor 11, and accumulates up to the level of the top of the dam 15, over which it flows into the tank 17. The presence of a relatively stagnant accumulation of liquid back of the darn 15 within the chamber 12 provides an opportunity for suspended particles to settle out of the liquid so they are not continuously re-circulated in the pumping system.

A cylinder 18 is preferably mounted on a normally vertical axis, With the lower extremity of this cylinder within the tank 17. A series of ports 19 are provided in the wall of the cylinder 18 at a point substantially below the level 16 of the solvent. In this arrangement, any floating particles of lint or other light materials are kept from entering into the circulating portion of the solvent. The pressurized movement of the solvent is obtained through the action of the piston assembly con nected to the lower extremity of the piston rod 20. The piston assembly includes the lower plate 21 and the upper plate 22 which are axially spaced and fixed with respect to the piston rod 20. The upper plate is pinned in position by the taper pin 23, and the lower plate 21 is secured by the bolt 24. A moving plate 25 is slidably mounted on the piston rod 20, and is grooved at its periphery to accommodate the sealing ring 26 operating against the inside of the wall of the cylinder 18. The ring 26 is preferably formed of a plastic material corn-v monly known by the trademark Teflon, as this material has been found particularly suitable to resist attack by the standard commercial solvent materials.

The moving plate 25 is provided with openings as shown at 27 and 28, these being covered by the upper plate 22 when the moving plate 25 is at its uppermost position with respect to the piston rod 20. This condition corresponds to a down stroke by the piston rod 20. On the upstroke of the piston rod, the frictional engagement of the sealing ring 26 against the walls of the cylinder 18, together with the effect of gravity on the plate 25 itself, will cause the plate to move relatively downward into the position shown in FIGURE 1 against the lower plate 21. This corresponds to upward movement of the piston 20, and permits liquid above the piston assembly to fiow through the openings 27 and 28 into the lower portion of the cylinder.

Subsequent downward movement of the piston will cause the liquid to move outward under pressure through the conduit 29. The position of the piston assembly at the downstroke is shown in dotted lines at 30 in FIG- URE 1. Applicant has found it preferable to generate approximately 20 to 25 pounds per square inch in the output line 29 as the best compromise for supplying the conventional spray guns within the chamber 12. A pressure much in excess of this will tend to induce too fine a spray, resulting in excessive vaporization. Too much reduction of pressure below this recommended figure will reduce the effectiveness of the spray in removing the accumulations of paint from the masks.

The pumping device provided by this invention contains several features developed for reducing the vapor loss and also vapor damage. The walls of the cylinder 18 are provided with a group of projections as shown at 31 and 32 in FIGURE 1. These extend inwardly, and provide a support for the barrier plate 33. Any tendency for the liquid within the cylinder 18 to splash during the action of the piston assembly or to squirt around the periphery of the piston as a result of an incomplete seal, will be confined by the barrier plate 33 so that spray will not be projected into the upper area of the cylinder. The position of the plate 33 may be kept as close as possible to the liquid level :16 by mounting the plate in such a manner that it can be moved upwardly by engagement with the hub of the upper piston plate 22.

Referring particularly to FIGURES 2 and 3, the upper extremity of the piston rod 20 is extended by the coupling 34 for connectign with the piston rod 35 associated with the air cylinder 36. The air cylinder 36, and the control valve mechanism generally indicated at 37, are conventional and form no part of the present invention. The valve-control rod 38 carries the adjustable abutments 39 and 40 which can be placed at any desired point to deter-mine the stroke of the piston rod 20, as these abutments operate in conjunction with the valve mechanism 37 in a conventional manner.

It is preferable to incorporate a vapor-confinement plate 41 in the piston rod assembly, and it is most convenient to mount this plate between the coupling 34 and a nut 42. The valve-actuating plate 43 cooperates with the follower 45 in a conventional manner for inducing movement of the actuating rod 38. The upper extremity of the cylinder 18 should be vented as shown at 44 to prevent a buildup of pressure in the vapors which would tend to enter into the seal unit 45 mounted on the cylinder head 46. The cylinder head preferably includes a ventilation chamber 47 which can be subject to either pressure or vacuum through the conduit 48. The bore provided for the insertion of the screw 49 can convenient- -ly be continued to provide communication with the chamber 47, with the vertical passage occupied by the conduit 48 being disposed to intersect this passage to form a continuous communication. In the case of the application of pressure through the conduit 48, a flow will tend to be established into the chamber 47 through the opening traversed by the piston rod '35, exhausting through the vents 44. Where vacuum is applied, any accumulation of vapor in the chamber 47 will tend to be drawn off through the conduit 48. In either case, the seal 46 is protected against the vapors entering into the seal around the periphery of the rod 35.

The particular embodiments of the present invention which have been illustrated and discussed herein are [for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is my intent to claim the entire invention disclosed herein, except as I am limited by the prior art.

I claim:

1. In combination with a cleaning chamber having a side opening, a pressurized system for inducing circulation of a solvent, said system comprising:

a tank disposed to receive liquid via said opening accumulating in said cleaning chamber;

a dam disposed at said opening to maintain a predetermined depth of liquid in said chamber; and

a pump for inducing flow of liquid trorn said tank and into said cleaning chamber, said pump including:

a normally vertical cylinder having an ,inlet communicating with said tank below the level maintained by said dam;

a head normally secured to said cylinder, said head having an opening for receiving a piston rod, and having a ventilation chamber communicating with said opening,

a piston rod mounted for reciprocation in said cylinder and cylinder head opening;

a seal surrounding said piston rod and mounted on said cylinder head, said piston rod traversing said ventilation chamber in extending ttrom the interior of said cylinder to said seal,

means for reciprocating said piston rod;

a piston assembly secured to the normally lower extremity of said piston rod, and including axially spaced transverse plates each occupying less than the full cross-section of said cylinder and fixed to said piston rod, and a movable plate in sealing engagement with the walls of said cylinder and interposed between said transverse plates, and slidably mounted on said piston rod, said movable plate having at least one opening covered by the upper of said transverse plates when said movable plate is in contact therewith, said opening being uncovered when said movable plate is in contact with the lower of said transverse plates to provide communication between portions of said cylinder above and below said movable plate,

a barrier plate disposed within said cylinder above said piston assembly and traversed freely by said piston rod, said cylinder having-support means for said barrier plate providing fireedom of movement of said barrier plate above said support means; and

a vapor-confinement plate secured to said piston rod above said barrier plate, and extending in close proximity to the walls of said cylinder.

2. In combination with a cleaning chamber having a side opening, a pressurized system for inducing circulation of a solvent, said system comprising:

a tank disposed to receive liquid via said opening accumulating in said cleaning chamber;

a dam disposed at said opening to maintain a predetermined depth of liquid in said chamber; and

a pump for inducing flow of liquid from said tank and into said cleaning chamber, said pump including:

a normally vertical cylinder having an inlet communicating with said tank below the level maintained by said dam;

a head normally secured to said cylinder, said head having an opening for receiving a piston rod, and having a venitilation chamber communicating with said opening,

a piston rod mounted for reciprocation in said cylinder and cylinder head opening;

a seal surrounding said piston rod and mounted on said cylinder head, said piston rod traversing said ventilation chamber in extending from the interior of said cylinder to said seal,

means for reciprocating said piston rod;

a piston assembly secured to the normally lower extremity of said piston rod; and

a barrier plate disposed within said cylinder above said piston assembly and traversed freely by said piston rod, said cylinder having support means for said barrier plate providing freedom of movement of said barrier plate above said support means.

3. In combination with a cleaning chamber, a pressurized system for inducing circulation of a solvent, said system comprising:

a tank disposed to receive liquid accumulating in said cleaning chamber;

a dam disposed at said opening to maintain a predetermined depth of liquid in said chamber; and

a pump for inducing fl-ow of liquid from said tank and into said cleaning chamber, said .pump including:

a normally veritical cylinder having an inlet communicating with said tank;

a head normally secured to said cylinder, said head having an opening for receiving a piston rod,

a piston rod mounted for reciprocation in said cylinder and cylinder head opening;

means for reciprocating said piston rod;

a piston assembly secured to the normally lower extremity of said piston rod, and including axially spaced transverse plates each occupying less than the full cross-section of said cylinder and fixed to said piston rod, and a movable plate in sealing engagement with the walls of said cylinder and interposed between said transverse plates, and slidably mounted on said piston rod, said movable plate having at least one opening covered by the upper of said transverse plates when said movable plate is in contact therewith, said opening being uncovered when said movable plate is in contact with the lower of said transverse plates to provide communication between portions of said cylinder above and below said movable plate,

a barrier plate disposed within said cylinder above said piston assembly and traversed freely by said piston rod, said cylinder having support means for said barrier plate providing freedom of movement of said barrier plate above said support means, and

a vapor-confinement plate secured to said piston rod above said barrier plate, and extending in close proximity to the walls of said cylinder.

4. In combination with a cleaning chamber, a pressurized system for inducing circulation of a solvent, said system comprising:

a tank disposed to receive liquid accumulating in said cleaning chamber;

5 6 a dam disposed at said opening to maintain a predetera barrier plate disposed within said cylinder above said mined depth of liquid in said chamber; and piston assembly and traversed freely by said piston a pump for inducing flow of liquid from said tank and Said Cylinder having Support means for Said into said cleaning chamber, said pump including; barrier plate providing freedom of movement of said a cylinder having an inlet communicatingwith said 5 barrier Plate a'bovfi said Support meanstank; a head normally secured to said cylinder, said head References Clted by the Exammer having an opening for receiving a piston rod, UNITED STATES PATENTS a piston rod mounted for reciprocation in said 2,287,396 6/ 1942 Roth 137-575 cylinder and cylinder head opening; 10 2,931,313 4/1960 Hughes 103-178 means for reciprocating said piston rod; a piston assembly secured to the normally lower CARY NELSON Prmary Examiner extremity of said piston rod; and W. CLINE, Assistant Examiner. 

4. IN COMBINATION WITH A CLEANING CHAMBER, A PRESSURIZED SYSTEM FOR INDUCING CIRCULATION OF A SOLVENT, SAID SYSTEM COMPRISING: A TANK DISPOSED TO RECEIVE LIQUID ACCUMULATING IN SAID CLEANING CHAMBER; A DAM DISPOSED AT SAID OPENING TO MAINTAIN A PREDETERMINED DEPTH OF LIQUID IN SAID CHAMBER; AND A PUMP FOR INDUCING FLOW OF LIQUID FROM SAID TANK AND INTO SAID CLEANING CHAMBER, SAID PUMP INCLUDING: A CYLINDER HAVING AN INLET COMMUNICATING WITH SAID TANK; A HEAD NORMALLY SECURED TO SAID CYLINDER, SAID HEAD HAVING AN OPENING FOR RECEIVING A PISTON ROD, A PISTON ROD MOUNTED FOR RECIPROCATION IN SAID CYLINDER AND CYLINDER HEAD OPENING; MEANS FOR RECIPROCATING SAID PISTON ROD; A PISTON ASSEMBLY SECURED TO THE NORMALLY LOWER EXTREMITY OF SAID PISTON ROD; AND A BARRIER PLATE DISPOSED WITHIN SAID CYLINDER ABOVE SAID PISTON ASSEMBLY AND TRAVERSED FREELY BY SAID PISTON ROD, SAID CYLINDER HAVING SUPPORT MEANS FOR SAID BARRIER PLATE PROVIDING FREEDOM OF MOVEMENT OF SAID BARRIER PLATE ABOVE SAID SUPPORT MEANS. 